As this type of system, for example, there is proposed a system in which a power transmission period for power transmission and a communication period for signal transmission from a power receiving apparatus to a power transmission side are alternately provided, and in which transmitted power is weaken in the communication period in comparison with the power transmission period. Here, in particular, it is proposed to realize the stop of the power transmission corresponding to the detection of a foreign body by moving into a standby state if the communication has a time-out error (refer to Patent literature 1).